Electrical carbonization of coal



A 8 R. B. STITZER V 2,127,542-

EJ 'JECTRICAL CARBONIZATION OF COAL Filed Aug. 14, 1935 2 Sheets-Sheet 1Ed/ph a SflfZer 4 INVEN TOR BY v ATTORNEY 2 Sheets-Sheet 2 FIG; 3

R. B. STITZERI ELECTRICAL CARBONIZATION 0F COAL Filed Aug. 14, 1935 Aug.23, 1938.

FIG. 4

INVENTQR ATTQRNEY I! 14 1/4 via 1 1 144 ap, 5. Sfifze/ Patented Aug. 23,1938 UNITED STATES ELECTRICAL CARBONIZATION 0F COAL Ralph B. Stltzer,Shefiield, Ala Application August 14, 1935, Serial No. 36,165

10 Claims.

(Granted under theact oi. March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) This application is made underthe act of March 3, 1883 as amended April 30, 1928, and the inventionherein described may be manufactured and used by or for the Governmentfor governmental purposes without the payment to me of any royaltythereon.

This invention relates to the process of electrical carbonization ofsolid carbonizable materials, particularly the'carbonization ofbituminous coal to form a coke suitable for domestic and industrialuses. 7

One of the objects of this invention is to provide a continuous methodand an efficient means for the carb'onization of solid carbonizablematerials in which electrical current is used as a source of the heatrequired for the operation. Another object of this invention is toeliminate the difliculties encountered in the carbonization of thosecoals which become plastic prior to carbonization. Still another objectof this invention is to provide a means for the withdrawal of thevolatile carbonizatlon products, which is a particularly serious problemwhen highly coking coals are carbonized. Other objects of the inventioninclude the provision of a method for the I the coke residue intofragments sufliciently reduced to facilitate removal from the retort. It

has been proposed also to heat a charge centrally with an electricalresistor and continue the passage of current through the coke formedaround the resistor until the entire charge is carbonized, followed bythe removal ofthe coke, thereby presenting a discontinuous operation,These and other processes, of which the above examples are.illustrative, have certain'disadvantages, each of which may include oneor more of'the following: First, the process is discontinuous; second,coking coals adhere to the heating elements during the time in whichthey are plastic and the car-' bonized residue prevents rapid heattransfer from the element to the coal mass; third, the plasticizing of acharge of coking coals seals the space between the particles ofchargeand makes the withdrawal of the volatile carbonization productsplication Ser. No. 52,853, filed December 4, 1935,

now U. S. Pat. No. 2,093,493 issued September 21, 1937, I have describedand claimed a process for making fuel gas from carbonlzable material andmore specifically a process for making a fuel'gas, consisting of amixture of coal gas and water gas, from coals I have found a continuousprocess for the electrical carbonization of solid carbonizable material.by electrically heating a column of solid carbonizable materialsurrounded by an envelope of carbonized material; by passing a supply ofinert gas downwardly through the inner'zone of 'the charge to keep theuncarbonized charge in the inner zone substantially free" from volatilecondensable carbonization products, by withdrawing the inert gas withthe volatile carbonization products upwardly through the outer zone ofthe carbonized portion of the charge which is separated from the innerzone by a gas impervious partition in the upper portion of the retort;by separating tar and other condensable materials from the gases sowithdrawn to form a fuel gas which may be used as a source of the inertgas admitted to the top of the column of the coal charge and by passinga portion of the fuel gas or other inert gas upwardly from the bottom ofthe retort to cool the coke below the zone of electrical heating and toheat the coal and coke above that zone.

In the accompanying drawings, which form a part of the specification,and wherein reference symbols refer to like parts whenever they occur,

Fig. l is a diagrammatic, vertical, sectional view of one formofapparatus for the embodiment of my process, A

Fig. 2 is a vertical, sectional view of the electrical carbonlzationretort,

plan view of the section a-n in a plan view of the sectionC-Cin of thesection D-D in into the inner zone in the top of retort-l, which issurrounded by partition 1. The charge of coal surrounded by theenvelope'of coke moves downwardly through the retort between a pair ofelectrodes or a plurality of electrodes, located in and flush with theopposite faces of the wall of the retort l, and represented byelectrodes- 8. The coal in the charge between the electrodes 3, iscarbonized largely from the heat produced by the passage of an:electrical current through the care ibon portion of the chargesurrounding the coal Fig. 3 ice plan view of the section A-A in.

portion of the charge, which serves as a resistor between electrodes 3,the current to the electrodes being supplied from the electrical servicelines 4, through the transformer 5. The hot coke which has passeddownwardly past electrodes 3, is cooled to a temperature below itsignition point in air by the upward passage of an inert gas, comprisedof steam and some fuel gas, admitted near the bottom of the retort at aplurality of points represented by inlet 6. The cooled coke is withdrawnfrom the bottom of the retort. The inert gas admitted at inlet 6, isheated by contact with the hot coke below the zone of the electrodes 3,and with additional heat obtained in the zone between the electrodespasses upwardly to heat the charge in the zone immediately above theelectrodes. A further amount of an inert gas, comprised of fuel gas, isadmitted through inlet 1, into the top of the inner zone in the top ofthe retort, into which the coal is charged and is passed downwardly in asufli'cient volume to keep the uncarbonized coal in the inner zonesubstantially free from condensable carbonization products. The gaseousmixture consisting of the inert gas admitted at the bottom of theretort, the inert gas admitted at the top of the inner zone of theretort, and the volatile carbonization products, pass upwardly throughthe coke in the outer zone at the top of the retort and are withdrawn atthe top of this outer zone. This mixture of gas from the retort,together with entrained solid and liquid particles, passes through theair condenser 8, where the major portion of the tarry matter is removed,and through the condenser 9, in which the major portion of the remainingvolatile condensable material in the gas from the retort is condensed byindirect cooling with water and separated from the gas. The gas from theretort from which substantially all the condensable volatile matter hasbeen removed passes into the inlet of the blower Ill, which serves tomaintain a substantially atmospheric pressure in the top of the outerzone of the retort I, and the gas delivered by blower I0, is treated inscrubbers II and I2 to remove valuable by-products, such as ammonia andother nitrogen compounds, and otherwise prepare the gas from the retortfor use as a fuel gas, such as by the removal of hydrogen sulfide andother sulfur compounds. A portion of this fuel gas is used as the supplyfor the inert gas admitted near the bottom of the. retort I, throughinlet 6, and into inlet 7, into the top of the inner zone of the retort.

vIn Fig. 2, the coke a, charged into the outer zone in the top of retortI, between the inner wall of the retort and partition 2, passesdownwardly and surrounds the charge of coal 1), which is fed into thetop of the inner zone surrounded by partition 2. The coke a, and thecoal 1), continue to pass downwardly into the zone between theelectrodes 3, in substantially the same relative position which thatoccupied on passing the bottom of partition 2. The coke a, serves as aresistor when it comes in contactwith the electrodes 3. and the heatproduced by the passage of the electrical current thru'the coke a,carbonizes the coal b, of the charge adjacent to it. The coal socarbonized in turn serves" as a resistor and the carbonization proceeds.Since, however, the

.operation is a continuous one, the amount of uncarbonized coal b, leftin the charge as it passes through the zone between the electrodes 3, iscontinually diminished until the coal 1), has been carbonized in itsentirety at the time, or shortly after it passes the elevation of thebottom of the electrodes 3. The inert gas admitted through the inlet 6,passes upwardly and cools the hot carbonaceous product in which the cokea, from the charge and the coke resulting" from the carbonization ofcoal b, is practically indistinguishable. The inert gas so heated servesto assist in the heating of the charge between the electrodes 3, and topreheat the charge in the zone above the elevation of the top of theelectrodes 3. The inert gas admitted through the inlet I, in the top ofthe inner zone of the retort, passes down-. wardly and keeps theuncarbonized coal 1), in the inner zone substantially free fromcondensable carbonization products. The volatile carbonization productsand the inert gas admitted at the bottom of the retort, together withthat admitted at the top of the inner zone of the retort, pass upwardlythrough the coke a, into the outer zone in the top of the retort and arewithdrawn from the top of this zone as the gas from the retort.

In Fig. 3, which is a plan view of a section near the top of retort I,the coke portion of the charge a, in the outer zone is shown separatedfrom the coal portion of the charge I), in the inner zone by partition2.

In Fig. 4, which is a plan view of a section of retort I, below theelevation of the bottom of the partition and above the elevation of thetop of the electrodes, the coke portion of the charge a. is shownenveloping the coal portion of the charge 27.

In Fig. 5, which is av plan view of a section of the retort I, throughthe electrodes, 0 represents the coke portion of the charge and thecarbonized portion of the charge, the two being practicallyindistinguishable at this point, surrounding the coal portion of chargeb, which has not yet become carbonized.

In Fig. 6, which is a plan view of a section of the retort I, betweenthe elevation of the bottom of the electrodes and the bottom of theretort, a represents the coke portion of the charge and the carbonizedportion of the charge, the two being practically indistinguishable atthis point.

It is evident that there are numerous factors which will influenceconditions for the most satisfactory operation of my invention, theactual limits of which cannot be established except by a detailed studyof each set of raw materials and the intermediate and finished productsinvolved.

The term solid carbonizable material shall mean and include solidcarbonizable material, which has not been subjected to a carbonizationprocess, and which may be heated to a sufliciently high superatmospherictemperature to remove the volatile products which it contains with theformation of a solid carbonized residue useful as a domestic orindustrial fuel or otherwise in the arts. Examples of solid carbonaceousmaterial include anthracite coal, non-coking and coking bituminouscoals, and materials of recent vegetable origin, such as woods and nutshells. The term "carbonized material shall mean and includeany solidcarbonaceous product resulting from the carbonization of a solidcarbonizable material. Examples of carbonized material include low andhigh volatile cokes and charcoal. In the operation of my process it ispreferred to use the carbonized portion of the charge derived fromsubstantially the same source as the uncarbonized portion of thecharge, 1. e., it is preferred to use a coke from bituminous coal inconnection with the carbonization of bituminous coal and it is preferredto use a hardwood charcoal derived from the same type of hardwood thatpreferably is such that it will pass through a l"- mesh and be retainedon a 0.25" mesh. Screenings which otherwise have little value formetallurgical purposes may be used for this purpose. Should thesescreenings contain a considerable excess 01 very fine material, such asbelow a 0.25" mesh, a small proportion of this material could beincorporated with the carbonizable, portionof the charge when thisportion of the charge is acoking coal. The size of thesolid carbonizablematerial preferably is such that this portion of the charge will passthrough a 2.5" mesh screen.

The ratio by weight of the carbonized material to the carbonizablematerial may vary within considerable limits, depending upon thematerials being processed. Using coke from bituminous coal and a cokingcoal of the sizes given above, the proportions may be varied from 10 toand 90 to 70% by weight, respectively.

The vertical retort shown in the respective- The partition in the top ofthe retort which forms the' outer and inner zones in which thecarbonized and carbonizable materials, respectively, are charged may beconcentric to the inner wall of a retort of uniform cross section fromtop to bottom or the cross section of the upper section of the retortand the partition within may be circular regardless of the nature oirthecross section of the zone above and be-r tween the electrodes. Thepartition forming the outer and inner zones extends from the top of theretort to an elevation located above the elevation of the top of theelectrodes, preferably to an elevation located above the top of theelectrodes equal to the distance between the electrodes, but may varywithin a reasonable range, depending upon the nature of the carbonizablematerial charged and the volume of inert gas per unit weight of chargepassed downwardly through the charge in the inner zone. a

The electrodes may be a pair, or a plurality of electrodes, located inand flush with opposite faces of the retort. The power supplied to theeleccarbonaceous residue through which it passes countercurrently, to atemperature below the ignition point of the carbonaceous residue in air:This rate has been found to be approximately 5 to 15 cubic feet ofretort gas per pound ofcarbonizable material charged in carbonizing acoking coal at the rate of 400 to 1000 pounds per square foot of retortcross section between the electrodes per hour. The inert gas admittedinto the bottom of the retort may be derived from any source, so long asit is not substantially reactive at any stage of the carbonizationprocess, or so long as it does notcontain any substantial proportion ofmaterial which is reactive at any stage in the carbonization process,and may include such materials as natural gas, producer gas, water gas,fuel gas produced by this process, and steam. It is ordinarily preferredto use steam as the inert gas without or with admixture of any of theabove mentioned gases. used during low temperature carbonization of acarbonizable material, as well as during a high temperaturecarbonization of a carbonizable ma; terial, in which the temperature ofthe carbonaceous material reaches 1 700 to 1900 F., particularly when itis necessary to produce a gas of high calorific value. Under suchconditions of high temperature carbonization, there is some dissociationof the water vapor but the operation of this process is so controlled asto prevent any substantial dissociation under the conditions for hightemperature carbonization used. Under these same conditions, thehydrocarbons in inert gas containing the same are decomposed andresult'in the production of a gas of lower calorific;

value than that obtained using steam alone. 7

The inert gas is admitted into the top of the inner zone of the retortthrough one, or a plurality of inlets, at such a rate as to keep theuncarbonized material in the inner zone substantially free fromcondensable products. This rate has beenfound to be approximately one tothree cubic feet of inert gas per pound of carbonizable. material incarbonizing a coking coal at the rate of 400 to 1000 pounds per squarefoot of retort cross section between the electrodes per hour. The inertgas admitted into the topoi the inner zone of the retort may be derivedfrom any source, so long as it is not substantially reactive at anystage of its contact with the carbonizable portion or carbonized portionof the charge, or so long as it does not contain any substantialproportion of material which is reactive at any stage of its contactwith the portions of the charge and may include such materials asnatural gas, producer gas, water gas, and fuel gas produced by thisprocess. It is ordinarily preferred to use fuel gas produced by thisprocess.

The gas from the retort which consists of the volatile carbonizationproducts and the inert gas admitted both at the bottom and at the top ofthe retort, is withdrawn from a plurality of the outlets at or near thetop of the outer zone in the top of the retort and is cooledstepwise toremove tarry matterand other condensable ma-' terials by such means asone or a plurality of aircooled condensers and one or a plurality ofwatercooled indirect condensers. The gas so treated may be used nowas asource of the supply of the inert gas used in the process or this gasmay be scrubbed to remove valuable'by-products, such as ammonia andother nitrogenous compounds. and otherwise prepare the retort gas foruse as a fuel gas, such as by the removal of hydrogen sulfide and othersulfur compounds. In either case only a portion of the treated gas fromthe retort is required to supplythe inert gas used in the process. Thepressure of the gas leaving the retort is maintained at substantiallyatmospheric pressure by means of a blower inthe condensing and scrubbingsystem, preferably between the two. At least a portion of the gasdischarged from the blower is maintained at a sufficient pressure to besupplied to the bottom and the top Steam alone may be of the retortwithout additional compression. Otherwise, the scrubbing system maybemaintained under a pressure at least equal to that required to deliverthe inert gas to the retort at the proper pressure.

The retort shell is built with standard masonry construction with arefractory lining. The electrodes, preferably made of carbon block, arelocated in opposite faces and flush with the inner faces of the retortin a mid-section of the retort. Substantially gas-tight chargingmechanisms, fitted into a gas-tight metal retort top, supply thecarbonized material and the carbonizing material from their respectivehoppers into the inner and outer zones, respectively, in the top of theretort.

I have found it possible to charge carbonizable material at a, muchhigher rate by using my process and apparatus as herein disclosed thanhas been possible heretofore. Coking coal is charged and carbonized at arate of more than 400 pounds per square foot of retort cross sectionbetween the electrodes per hour, as compared with a rate of less than100 pounds per square foot of retort section per hour, using anotherprocess and apparatus. I have found also that it is possible toaccomplish the carbonization using my process and apparatus hereindescribed by the use of a considerably smaller quantity of electricalenergy.

For instance, in the carbonization of a coking coal at the rate of 450pounds per square foot of retort cross section between the electrodesper hour, 310 kw. hr. per ton of coal charged were required as comparedto the other process and apparatus referred to above at the rate of 88pounds of coking coal per square foot of retort cross section per hour,350 kw. hr. per ton of coal were required.

It will be seen, therefore, that this invention actually may be carriedout by the modification of certain details without departing from itsspirit or scope.

I claim:

1; Process of carbonizing coking coal which comprises, charging cokecontinuously into an outer zone in the top of a vent retort of squarecross section, surrounding and gas-imperviously separated from an innerzone, with both zones open at the bottom and extending downwardly untilthey are adjacent to but above a heating zone in a substantiallyhorizontal section of the retort; charging the coal continuously intothe inner zone in the top of the retort; passing an electrical current,supplied to the'sides of the heating zone through the charge in theheating zone, the characteristics of the current being regulated so thatthe heat produced on passing through the charge in the heating zone issufficient to cause the coal to be substantially carbonized when it haspassed through the heating zone; passing a portion of the coal gassubsequently produced into the retort, near the bottom, countercurrentto the direction of flow of the charge to cool the coke below theheating zone and to heat the coal and coke above the heating zone;passin g'a small proportion of the coal gas subsequently produced intothe. top of the inner zone; withdrawing the retort gas, comprising thesmall proportion of coal gas admitted into the top of the inner zone,the volatilized products of carbonizatiomand the coal gas admitted nearthe bottom of the retort, from the top of the outer zone at the top ofthe retort; separating the condensable materials from the retort gas sowithdrawn to yield a coal gas; and

withdrawing-the cooled coke continuously from the bottom of the retort.

2. Process of carbonizing solid carbonizable material which comprises,charging carbonized carbonizable material continuously into an outerzone in the top of a vent retort of square cross section, surroundingand gas-imperviously separated from an inner zone, with both zones openat the bottom and extending downwardly until they are adjacent to butabove a heating zone in a substantially horizontal section of theretort; charging the solid carbonizable material continuously into theinner zone in the top of the retort; passing an electrical current,supplied to the sides of the heating zone through the charge in theheating zone, the characteristics of the current being regulated so thatthe heat produced on passing through the charge in the heating zone issuflicient to cause the solid carbonizable material to be substantiallycarbonized when it has passed through the heating zone; passing aportion of the fuel gas subsequently produced into the retort, near thebottom, countercurrent to the direction of flow of the charge to coolthe carbonized material below the heating zone and to heat the solidcarbonizable material and carbonized carbonizable material above theheating zone; passing a small proportion of the fuel gas subsequentlyproduced into the top of the inner zone; withdrawing the retort gas,comprising the small proportion of fuel gas admitted into the top of theinner zone, the volatilized products of carbonization and the fuel gasadmitted near the bottom of the retort, from the top of the outer zoneat the top of the retort; separating the condensable materials from theretort gas so withdrawn to yield a fuel gas; and withdrawing the cooledcarbonized product continuously from the bottom of the retort.

3. Process of making coke from coking coal which comprises, forming acolumn of the coal surrounded by a column of coke above a heating zonein a substantially horizontal section of a vertical retort with theinner zone above the heating zone containing the coal and the outer zoneabove the heating zone containing the coke, gasimperviously separatedfrom each other from the top of the retort to a location adjacent to theheating zone; passing an electrical current, supplied to the sides ofthe heating zone, through the charge in the heating zone, thecharacteristics of the current being regulated so that the heat producedon passing through the charge in the heating zone is suilicient to causethe coal to be substantially carbonized when it has passed through theheating zone but insuilicient to heat the coke in the heating zone tothe temperature ,of conversion of any substantial proportion of thesteam subsequently admitted in contact with the coke into water gas;passing steam into the retort, near the bottom, countercurrent to thedirection eie flow of the charge to cool the coke below the heating zoneand to heat the coal and coke above the heating zone; passing a smallamount of inert gas into the top of the inner zone; and withdrawing theretort gas, comprising the inert gas admitted into the top of the innerzone, the volatilized products of the carbonization and the steamadmitted near the bottom of the retort, from the top of the outer zoneat the top of the retort.

4. Process of making a carbonized material from a carbonizable materialwhich comprises, forming a column of the carbonized carbonizablematerial surrounded by a column of carbonized material above a heatingzone in a substantially horizontal section of a vertical retort with theinner zone above the heating zone containing the carbonizable materialand the outer zone above the heating zone containing the carbonized ma"-terial, gas-imperviously separated from each other from the top of theretort to a location ad- N jacent to the heating zone; passing anelectrical current, supplied to the sides of the heating zone, throughthe charge in the heating zone, the characteristics'of the current beingregulated so that the heat produced on passing through the charge in theheating zone is suiiicient to cause the carbonizable material tobensubstantially carbonized when it has passed through the heating zonebut insufiicient to heat the carbonized material in the heating zone tothe temperature of conversion of any substantial proportion of the steamsubsequently admitted in contact with the coke into water gas; passingsteam into the retort, near the bottom, countercurrent to the directionof flow oi the charge to cool the carbonized material below the heatingzone and to heat the solid carbonizable material and the carbonizedcarbonizable material above the heating zone; passing a small amount ofinert gas into the top'of the inner zone; and withdrawing the'retortgas, comprising the inert gas admitted into the top of the inner zone,the volatilized products of the carbonization and the steam admittednear the bottom of the retort, from thetop of the outer zone at the topof the retort.

5. Process of making coke from coking coal which comprises, passing anelectrical current,

supplied to the sides of the heating zone in a sub-' stantijaily'horizontal section or a retort, through heating zone, with thecharacteristics of the current being so regulated that the heat producedon passing through the charge in the heating zone is sufficient to causethe coal to be substantially; carbonized when it has passed'through theheating zone; passing an inert gas through the heating zonecountercurrent to the direction of flow oi the charge oi said zone;passing a small amount 0! an inert gas downwardly through only the coalportion of the charge above the heating zone to a location adjacent tothe heating zone; and withdrawing the retort gas, comprising the inertgas admitted into the top of the inner zone. the volatilized products ofthe carbonization and the inert gas passed through the heating zone,from the top or the outer zone at the top of the retort.

6. Process oi making carbonized material from produced on passingthrough the charge in the heating zone is sufllcient to cause thecarbonizable material to be substantially carbonized when it has passedthrough the heating zone; passing an inert gas through the heating zonecountercurrent to the direction of flow of the charge of said zone;passing a small amount of an inert gas downwardly through only the coalportion of the 1 charge above the heating zone to a location ad- ,iacentto the heating zone; and withdrawing the aromas retort gas, comprisingthe inert gas admitted into the top oi the inner zone, the volatilizedproducts of the carbonization and the inert gas passed through theheating zone, from the top of the outer zone at the top of the retort.

'1. Processor carbonizing coking coal which comprises, heating a sectionof a column of charge, which comprises coking coal surrounded by anenvelope oi coke, to a superatmospheric temperature suflicient tocarbonize the coal by passing an electrical current between electrodeslocated in contact with and on opposite sides of the section of thecharge, and by passing a cur- ,rent of inert gas upwardly thru thesection of the charge; passing inert gas downwardly thru a column-oicoal above the section of the charge to keep the .uncarbonized coalsubstantially free from condensable carbonization products; andwithdrawing the inert gas and the volatile carbonization products thruthe coke surrounding the coal above the section oithe charge, the cokebeing separated from the coal by a gas-impervionspartition.'

8. Process of --carbonizing solid carbonizable material which comprisesheating a section of a column of charge, which comprises solidcarbonizable material surrounded by an envelope of carbonizedcarbonizable material, to a superatmospheric temperature sumcient tocarbonize the solid carbonizable material by passing an electricalcurrent between electrodes located in contact with and on opposite sidesof the section of the charge, and by passing a current of inert gasupwardly thru the section oi the chargeypassing inert gas downwardlythru a column of solid carbonizable material above the section of thecharge to keep the uncarbonized solid carbonizable materialsubstantially free from condensable carbonization products; andwithdrawing the in-. ert gas and the volatile carbonization products.

thru the carbonized carbonizable material surthe section of the charge,the carbonized carbonizable material being separated from. the solidcarbonizable material by a gas-impervious partition.

9, Steps in the process of carbonizing coking coal which comprisespassing a current of inert gas downwardly thru a column oi the coalportion of the charge, which is surrounded by a coke portion of thecharge, the two portions being separated by a gas-impervious partitionas the charge approaches the zone of carbonization between electrodeatokeepthe uncarbonized coal substantially free from condensablecarbonization products; and withdrawing the inert gas and the volatilecarbonization products upwardly thru the coke portion of the charge.

10. Steps in the process oi carbonizing solid carbonizable materialwhich comprises passing a current of inert gas downwardly thru a column01' the solid carbonizable material portion of the charge, which issurrounded by a carbonized carbonizable material portion of the charge,the two portions being separated by a gas-impervious partition as thecharge approaches the zone of carbonization between electrodes, to keepthe uncarbonized solid carbonizable material substantially free fromcondensable carbonization products; and withdrawing the inert gas andthe volatile carbonization products upwardly thru the carbonizedcarbonizable material portion of the charge.

, RALPH B. STITZER.

CERTIFICATE OF CORRECTIOIL' Patent No. 2,127, 51,2. August 2 19 RALPH B.STITZER.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 52, for the word."carbonizable" read carbonaceous;and line 59, for "carbonaceous" read carbonizable; and that the saidLetters Patent should be read with this correction therein tlnt the samemay conform to -'the record of the case in the Patent Office.

Signed and sealed this 11th day of. October, A. D. 1958 Henry YenAradale (Seal) Acting Commissioner of Patents.

